Switching devices are typically data link layer devices that enable multiple network devices to communicate with each other or enable physical network (e.g., local area network (LAN) or wide area network (WAN)) segments to be interconnected into a single larger network. In the most general sense, switching devices transport data in the form of frames between input/output (I/O) ports. A frame is a logical grouping of information sent as a data link layer unit over a transmission medium. Each frame typically includes data payload sandwiched between header and trailer information. The terms cell, datagram, message, packet and segment are also used to describe logical information groupings at various layers of the OSI reference model and in various technology circles. As used herein, the term “frame” should be understood in its broadest sense, and can be defined to encompass other terms such as cell, datagram, message, packet, segment, etc.
Switching devices often employ switching fabrics that have multiple I/O ports coupled to each other. Each I/O port typically contains an input buffer that receives and stores frames until they can be transmitted to output buffers of other I/O ports. Frames transmitted to an output buffer are received and stored in that buffer until they can be subsequently transferred towards their ultimate network device destination. Users typically require that each switching device operate as quickly as possible in order to maintain a high data throughput rate. Unfortunately, output buffers may become congested with frames at times, which may lead to latency and blocking issues.
The use of the same reference symbols in different drawings indicates similar or identical items.